Blocks for ACF Fields <= 1.6.2 - Missing Authorization to Authenticated (Author+) Arbitrary ACF Field Value Disclosure via 'id' Parameter
Strategic Overview
- Status
- Patched in 1.6.3
- Affected Version
<= 1.6.2- CVSS
- 6.5Medium
- Weakness type
- CWE-862 · Missing Authorization
- CVE
CVE-2026-12428
At a glance
CVE-2026-12428 is a medium-severity Missing Authorization vulnerability in the Blocks for ACF Fields WordPress plugin, affecting versions <= 1.6.2. It carries a CVSS score of 6.5 (reachable over the network; low attack complexity; high confidentiality impact). Exploitation requires an authenticated account at Author level or above. The issue is fixed in version 1.6.3; sites on affected versions should update now. Disclosed July 2026, reported by thinnawarth mathuros.
Vulnerability Overview
The Blocks for ACF Fields plugin for WordPress is vulnerable to unauthorized access of data due to a missing capability check on the get_all_values() function in the /wp-json/acf-field-blocks/v1/values REST endpoint in versions up to, and including, 1.6.2. The permission_callback only verifies the generic publish_posts capability and the handler passes a user-supplied id parameter directly to get_field_objects() without verifying that the requesting user is authorized to read the target object. This makes it possible for authenticated attackers, with Author-level access and above, to read ACF field values from arbitrary posts (including private posts, drafts, posts by other users, and other ACF-supported objects) that they should not have access to.
Technical Analysis
The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user. A successful exploit has high impact on confidentiality.
CWE-862: Missing Authorization
Blocks for ACF Fields <= 1.6.2 carries this weakness at get_all_values(), and reaching it takes an account at Author level or above. A missing authorization check means a function is reachable by anyone who can reach the endpoint, because the code never asks whether the caller is allowed to perform the action.
Any user who can reach the endpoint gets to run an action reserved for higher-privileged roles, from reading protected data to changing settings or content. For Blocks for ACF Fields the fix is 1.6.3: builds <= 1.6.2 are affected, anything from 1.6.3 onward is not.
Remediation
Update to version 1.6.3, or a newer patched version
How does WordSec protect against this?
Because it turns on account access, WordSec's login security is the relevant layer: role-based two-factor, captcha and brute-force limits raise the cost of getting the account this needs. None of that substitutes for the fix: Blocks for ACF Fields 1.6.3 closes this, and updating the plugin is the step that ends it.
- Login Security
- Alerts
External References
Vulnerability data © Defiant, Inc., provided under the Wordfence Intelligence T&C